1. Field of the Invention
The present invention relates generally to radiation devices. More particularly, the invention concerns an apparatus for irradiating various articles with ultraviolet radiation from a radiation source such as a plurality of ultra-violet lamps.
2. Discussion of Prior Art
Ultra-violet radiation is widely used in industry and science for sterilization through inactivation of microorganisms, for inducing and promoting various types of photochemical reactions and for controllably exposing various types of photosensitive materials. By way of example, U.S. Pat. No. 5,175,437 issued to the present inventor describes an apparatus for irradiating an object such as a specimen of material with ultraviolet radiation at a selected long, short or mid-wave length. Similarly, U.S. Pat. No. 3,936,186 issued to Boland et al discloses an apparatus for exposing diazo printing plates and the like of the character that are used in the graphic arts field. In like manner, U.S. Pat. No. 5,288,647 issued Zimlich, Jr. et al relates to a method by which polynucleotide specimens can be irradiated particularly for the purpose of fixing them to a substrate.
Ultraviolet light (UV), which is electromagnetic radiation in the region of the spectrum located between X-rays and visible light, is typically divided into three principal ranges, namely long wave, mid-range, and short wave. For each of these UV ranges specific applications have been developed.
As a general rule, the desired ultraviolet wavelength is obtained from a fluorescent style tube that is an electric discharge device that uses a low-pressure mercury vapor arc to generate ultraviolet energy. The ultraviolet energy released in typical, commercially available fluorescent tubes is primarily at the wavelength of about 254 nanometers. The fluorescent tubes can be modified to release other ultraviolet wavelengths by the use of phosphors, which have the ability to absorb the ultraviolet energy and re-radiate it in other wavelengths. For example, long wave ultraviolet of about 365 nanometers and mid-range ultraviolet of about 300 nanometers are created by coating the inside of the fluorescent tubes with the proper phosphors which convert the short wave ultraviolet.
In the past ultraviolet irradiation of selected articles has been accomplished using a single UV range fluorescent tube mounted within a suitable enclosure. In order to eliminate white light generated by the UV tube, some prior art devices make use of a UV transmitting light blocking filter that is typically mounted in front of the UV tube.
In the past, when it was desired to obtain two UV wave lengths from the radiation device, two UV tubes emitting two levels of UV radiation were mounted side by side within the device, and an appropriate filter was placed in front of each tube.
In the apparatus disclosed in the previously identified U.S. Pat. No. 5,175,347 issued to the present inventor, a different and novel technique was used to irradiating an object, with ultraviolet radiation at a selected long, short or mid-wave length. More particularly, in this prior art apparatus, a plurality of ultraviolet sources, each emitting radiation at a different wave length, were mounted within a rotatable array so that a selected one of the sources could be moved into alignment with the specimen and automatically energized by merely rotating the array.
As will be better understood from the discussion that follows, the present invention enables the controlled irradiation of a specimen with UV at selected wavelengths through the use of a novel wavelength conversion means that can be interposed between the UV source and the specimen.
It is an object of the present invention to provide an apparatus for expeditiously irradiating an object with ultraviolet radiation at a selected UV wavelength.
More particularly, the apparatus of the invention comprises a plurality of ultraviolet sources, each emitting radiation at a first wave length. The UV sources are mounted within a housing that also supports a novel conversion plate that can be interposed between the UV sources and the specimen and functions to convert the UV to a second wavelength.
Another object of the invention is to provide an apparatus of the aforementioned character in which the conversion plate is slidably carried by the housing.
Another object of the invention is to provide an apparatus as described in the preceding paragraphs in which the specimen can be irradiated with ultraviolet radiation at a selected wave length between about 254 nanometers and about 365 nanometers.
Still another object of the invention is to provide an apparatus of the class described, which includes strategically located reflectors for reflecting the ultraviolet radiation in a direction toward the specimen. Another object of the invention is to provide an apparatus as described in the preceding paragraphs in which a filter for blocking white light from the UV sources is interposed between the specimen and the UV sources.
Yet another object of the invention is to provide an apparatus of the character described which is of a simple, compact construction that is easy to use and can be inexpensively manufactured.